A generator such as a permanent magnet generator may be configured to produce flat-topped alternating current (AC) waveforms. The amplitude and frequency of these waveforms are proportional to the rotational speed of the generator. The generator may be used as a precision tachometer, for example, in a motion control system, if the output signals of the tachometer are suitably commutated.
The performance of such a unit depends on the unit's ability to produce a nearly perfect DC output for a constant rotation speed. The tachometer is designed to create a constant magnetic field strength and excite a constant number of turns as the magnet rotates, so that the only variable affecting output voltage is the rotational speed.
However, generator devices configured, for example, as the foregoing tachometer device, include a variety of residual errors. Error sources may include, but are not limited to, magnetic material properties, mechanical roundness, flatness, asymmetry and alignment, winding placement, magnetic leakage paths, shielding effects, and the influence of nearby magnetic sources or materials. The errors manifest themselves primarily as ripple components in the signal related to harmonics of the rotational frequency and the pole count of the device.
Practical manufacturing methods and non-ideal material properties inevitably result in an imperfect product. Accordingly, it is desirable to implement a method to compensate for the residual errors found in generator devices. In addition, such a method should be cost-effective, not resulting in the expenditure of large resources, and be compatible across an entire line of device designs. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.